The field of this disclosure relates generally to breast pumps and more particularly to a breast pump that mimics the suckling of a nursing infant thereby providing an efficient and comfortable pump for nursing mothers.
Breast pumps, whether electric or manually operated, typically include at least one breast cup configured for sealing placement over a nursing mother's breast. A vacuum pump is operatively connected to the breast cup for applying a vacuum to the mother's breast within the cup. More specifically, commonly configured breast cups have a central passage for receiving at least the mother's nipple and more typically some adjacent portion of the mother's breast, allowing vacuum pressure to be applied to the mother's nipple for extracting milk. During use, the vacuum pressure is often applied in pulses, with the central passage being sometimes vented between pulses. A bottle or other suitable receptacle is usually in fluid connection with the breast cup to collect the extracted milk.
When a baby is placed at the breast to be fed, a cascade of events occurs. The baby places their mouth and tongue (latches) with a negative pressure of approximately 30 mm Hg to the nipple/areola and stimulates milk ejection through a series of quick, shallow sucks referred to as non-nutritive suckling. Non-nutritive suckling consists of stable lengths of sucking bursts and duration of pauses. The average pressure of non-nutritive suckling is approximately 70 to 90 mm Hg. As the baby non-nutritive suckles, the mother's brain recognizes the stimulation at the breast and a reflex arc occurs. This reflex arc causes an oxytocin release from the posterior pituitary, which ultimately leads to milk ejection. Oxytocin is a hormone that acts on the myoepithelial cells eliciting a contraction of the smooth muscle cells around the alveolus in the breast. The contraction of these cells actively pushes the milk into the ducts toward the nipple, where the milk is ejected. The baby acts as a milk collector by means of nutritive suckling with strong, even draws. During nutritive suckling the movement of the tongue, jaw, and swallowing facilitates milk flow. The average pressure for nutritive suckling is approximately 75-100 mm Hg.
Vacuum pressure needed to extract milk using a conventional breast pump is substantially higher than that of a suckling infant. For example, the vacuum pressure applied to the mother's breast by conventional breasts pump is often 200 mm Hg (millimeters of mercury) and greater. Over the full transfer period, such high vacuum pressure can often be painful to the mother and in some cases can irritate or damage the mother's breast tissue. Moreover, applying pulses of vacuum pressure to the mother's breast does not adequately simulate the peristaltic movements of an infant's mouth and tongue during breastfeeding to apply oral pressure to the mother's breast.
There is a need, therefore, for a breast pump that is more comfortable to a nursing mother and more effectively simulates the oral pressure and movement of an infant during feeding.